1. Field of the Invention
The present invention relates to a slider preferable for a concealed type slide fastener and the concealed type slide fastener equipped with the same slider.
2. Description of the Related Art
Conventional typical slide fasteners are classified broadly into two types, i.e. a normal type and a concealed type. In a normal type slide fastener 100, as shown in FIG. 8, a multiplicity of fastener elements 102 are mounted across the front surfaces or front and rear surfaces of opposing element mounting edge portions of two fastener tapes 101 so as to constitute right and left fastener stringers 103. Each of the fastener elements 102 of the right and left fastener stringers 103 is inserted through a guide passage of a slider 104 together with an element mounting edge portion of a fastener tape 101. The slider 104 includes a slider body 105 and a pull tab 106 attached to the same slider body 105.
The slider body 105 has upper and lower blades 105a, 105b and a connecting post 105c for connecting the upper and lower blades 105a, 105b. This connecting post 105c connects the upper and lower blades 105a, 105b and in a space between the upper and lower blades 105a and 105b, defines a Y-shaped element guide passage in which right and left shoulder mouths for separating and passing right and left fastener element rows 107 of the right and left fastener stringers 103, the fastener element rows constituted of a multiplicity of the fastener elements 102, separately and a rear mouth for passing the engaged fastener element rows 107 are communicated with each other. At right and left side edges of the upper and lower blades 105a, 105b, there are provided upper and lower flanges 105a-1, 105b-1 which are at right angle to the upper and lower blades 105a, 105b and approaching each other. The fastener tape 101 is passed through a gap between the upper and lower flanges 105a-1 and 105b-1 entirely across both inside and outside of the slider body 105.
That is, in this normal type slide fastener 100, the fastener element row 107 disposed on the same plane of the fastener tape 101 is passed through the element guide passage of the slider body 105 without folding back the fastener tape 101. Thus, whether the slide fastener 100 is opened or closed, the fastener elements 102 are exposed outside. At the same time, a sewing thread 108 of the fastener element row 107 with respect to the fastener tape 101 is also exposed outside.
On the other hand, in recent years, use of the concealed type slide fastener in which the fastener elements are invisible from a surface side of the slide fastener has been demanded more and more in design viewpoints and this concealed type slide fastener has been used in clothes, shoes and the like frequently. An example of an ordinary concealed type slide fastener has been disclosed in, for example, Japanese Patent No. 3439605 (patent document 1). In case of a concealed type slide fastener 200, as shown in FIG. 9, folded-back side edge portions 201a are formed by folding back the opposing element mounting edge portions of two fastener tapes 201 into a U shape along a length direction thereof and a multiplicity of fastener elements 202 are attached to a bottom face side of folded-back pieces 201a-1 of the folded-back side edge portions 201a so as to constitute right and left fastener stringers 203.
Each of fastener element rows 204 of the right and left fastener stringers 203 is passed through the guide passage of a slider 205 together with the folded-back piece 201a-1 of the fastener tape 201. At this time, other portion of each fastener tape 201 than the folded-back piece 201a-1 and the fastener element row 204 covers the front surface side of a slider body 206. Thus, the body 206 of the slider 205 applied for this kind of the concealed type slide fastener is usually provided with a guide post 206c which is extended from the shoulder mouth to the rear mouth in the central portion in the right and left direction of the lower blade 206b, and element guide flanges 206d each having an inverted L shaped section, the element guide flanges comprising rising portions 206d-1 which rise along right and left side edges of the lower blade 206b and horizontal portions 206d-2 extended horizontally from top ends of the rising portions in a direction of approaching each other.
A pull tab mounting portion 206c-1 is provided protrudedly on a top face of the guide post 206c and a pull tab 207 is mounted on the same pull tab mounting portion 206c-1 such that it can be moved freely in a back and forth direction. This pull tab mounting portion 206c-1 is projected upward between the opposing tape folded-back portions of the right and left fastener stringers 203. Thus, the fastener element rows 204 and their sewing threads are hidden behind the rear face of the fastener tapes so that they are invisible from outside and when the slide fastener 200 is closed, an opening/closing portion of a product on which the same fastener 200 is mounted is exposed only in the form of a seam line, thereby providing a neat appearance.
However, instead of the concealed type slide fastener having such a complicated structure, for example, a concealed type slide fastener proposed in U.S. Pat. No. 5,008,986 (patent document 2) has been known. According to the patent document 1, without changing the structure of the upper and lower blades in the ordinary slide fastener shown in FIG. 8, the fastener element row attached to the top face side of the fastener tape is attached to the bottom face side thereof. However, only if the fastener element row is attached to the bottom face side of the fastener tape, a gap is generated between opposing side edges of the fastener tapes and as a consequence, the fastener element row is still visible through that gap from outside.
According to the same document 1, the side edges of the fastener tapes are extended more to the coupling head side of the fastener elements than the normal position, and when the slide fastener is opened or closed, particularly when closed, the opposing side edges of the fastener tapes press each other so that they makes firm contact with each other and as a consequence, the fastener element rows are invisible from outside. Further, if the fastener tape is provided with waterproofness, no water enters via the fastener elements through the gap between the side edges because the opposing side edges of the fastener tapes press each other so that they make firm contact with each other and consequently, this is a structure suitable for shoes, waterproof clothing and the like.
However, according to the patent document 2, although the fastener element row is located on the bottom face of the fastener tape, because it is sewed with sewing thread without folding back the fastener tape, that sewing thread itself is exposed on the surface. If the concealed type slide fastener disclosed in the patent document 2 is adopted to a product which strikes violently and repeatedly such as various kinds of sport shoes, if the sewing thread is exposed outside as described above, an external force is applied to the same sewing thread or the sewing thread is caught by a tool nearby so that it is likely to be cut out. Further, if the same slide fastener is adopted to for example waterproof clothes, water is likely to enter through the seam line because the seam line is exposed outside, so that no expected waterproof effect is obtained.
On the other hand, in case of the slider 205 of concealed type slide fastener having an ordinary structure shown in FIG. 9, if it is intended to adopt this to clothing which is fit to human body such as shoes, the inside face of the folded-back portion of the folded-back side edge portion 201a having the U-shaped section of the fastener tape 201 comes into firm contact with an end of a horizontal portion 206d-2 of an inverted L-shaped flange portion 206d rising from each of the right and left edges of the lower blade 206b of the slider 205 during its sliding and consequently, sliding resistance is increased so that wear is accelerated at that portion thereby possibly affecting the durability. Further, in case of the concealed type slide fastener 200 having this ordinary structure, if a pulling force in a width direction of the fastener tape is applied to the fastener tape 201, a portion continuous from the tape main portion of the folded-back side edge portion 201a is pulled strongly by the end of the horizontal portion 206d-2 of the inverted L-shaped flange portion 206d, so that the fastener element 202 existing among the lower blade 206b, the guide post 206c and the inverted L-shaped flange portion 206d is easily raised obliquely and its stable posture cannot be maintained. As a result, this can affect the engagement of the fastener elements 202 or the folded-back side edge portion 201a which is folded back into the U shape is deformed in an opening direction thereby damaging the appearance in fashion viewpoints.